1 files changed, 97 insertions, 0 deletions
diff --git a/dom/abort/AbortFollower.h b/dom/abort/AbortFollower.h
new file mode 100644
index 0000000000..8c2509781a
--- /dev/null
+++ b/dom/abort/AbortFollower.h
@@ -0,0 +1,97 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_AbortFollower_h
+#define mozilla_dom_AbortFollower_h
+
+#include "jsapi.h"
+#include "nsISupportsImpl.h"
+#include "nsTObserverArray.h"
+#include "mozilla/WeakPtr.h"
+
+namespace mozilla::dom {
+
+class AbortSignal;
+class AbortSignalImpl;
+
+// This class must be implemented by objects who want to follow an
+// AbortSignalImpl.
+class AbortFollower : public nsISupports {
+ public:
+  virtual void RunAbortAlgorithm() = 0;
+
+  // This adds strong reference to this follower on the signal, which means
+  // you'll need to call Unfollow() to prevent your object from living
+  // needlessly longer.
+  void Follow(AbortSignalImpl* aSignal);
+
+  // Explicitly call this to let garbage collection happen sooner when the
+  // follower finished its work and cannot be aborted anymore.
+  void Unfollow();
+
+  bool IsFollowing() const;
+
+  AbortSignalImpl* Signal() const { return mFollowingSignal; }
+
+ protected:
+  virtual ~AbortFollower();
+
+  friend class AbortSignalImpl;
+
+  WeakPtr<AbortSignalImpl> mFollowingSignal;
+};
+
+/*
+ * AbortSignalImpl is a minimal implementation without an associated global
+ * and without event dispatching, those are added in AbortSignal.
+ * See Bug 1478101
+ */
+class AbortSignalImpl : public nsISupports, public SupportsWeakPtr {
+ public:
+  explicit AbortSignalImpl(bool aAborted, JS::Handle<JS::Value> aReason);
+
+  bool Aborted() const;
+
+  // Web IDL Layer
+  void GetReason(JSContext* aCx, JS::MutableHandle<JS::Value> aReason);
+  // Helper for other DOM code
+  JS::Value RawReason() const;
+
+  virtual void SignalAbort(JS::Handle<JS::Value> aReason);
+
+ protected:
+  // Subclasses of this class must call these Traverse and Unlink functions
+  // during corresponding cycle collection operations.
+  static void Traverse(AbortSignalImpl* aSignal,
+                       nsCycleCollectionTraversalCallback& cb);
+
+  static void Unlink(AbortSignalImpl* aSignal);
+
+  virtual ~AbortSignalImpl() { UnlinkFollowers(); }
+
+  void SetAborted(JS::Handle<JS::Value> aReason);
+
+  JS::Heap<JS::Value> mReason;
+
+ private:
+  friend class AbortFollower;
+
+  void MaybeAssignAbortError(JSContext* aCx);
+
+  void UnlinkFollowers();
+
+  // Raw pointers.  |AbortFollower::Follow| adds to this array, and
+  // |AbortFollower::Unfollow| (also called by the destructor) will remove
+  // from this array.  Finally, calling |SignalAbort()| will (after running all
+  // abort algorithms) empty this and make all contained followers |Unfollow()|.
+  nsTObserverArray<RefPtr<AbortFollower>> mFollowers;
+
+  bool mAborted;
+};
+
+}  // namespace mozilla::dom
+
+#endif  // mozilla_dom_AbortFollower_h